While conventional ultrasonic humidifiers have a water particle size of 1 to 5 μm, air washer humidifiers have a water particle size of 0.3 μm or less. Accordingly, since the sizes of water particles scattered from air washer humidifiers are smaller than those of ultrasonic humidifiers, the water particles from the air washer fly further away and serve as a cleaner that catches particles suspended in the indoor air. Due to such an advantage of purifying indoor air of air washer humidifiers, ultrasonic humidifiers are being replaced by air washer humidifiers. However, humidification efficiency of air washer humidifiers is very low because water particles are scattered by air, not by ultrasonic vibration. To compensate for such low efficiency in humidification amount, an attempt to maximize surface area by using a plurality of disks having a large diameter and a thin thickness and applying irregularities to surfaces of the disks have been made.
In the case of an air washer disk, water should be adsorbed onto a surface of the disk and then should be scattered by air. As such, when a hydrophilic resin is used as a material of a disk, moisture adsorption is satisfactorily accomplished, but the resin swells due to moisture adsorption. Accordingly, the disk may be deformed. In addition, when a hydrophobic resin is used to prevent deformation due to swelling, deformation due to swelling may be prevented, but a humidification amount is decreased due to low surface moisture adsorption rate. To compensate for such problems, a method of coating a hydrophobic resin with a glue, e.g., a hydrophilic resin, has been used. However, upon use of such a method, the hydrophilic resin is detached as use time elapses, whereby floating matter is formed, a disk surface becomes dirty, a humidifier is contaminated, and humidification efficiency is decreased. Accordingly, consumer satisfaction is decreased.
Therefore, there is a need for a resin that provides sufficient humidification and allows a disk not to be deformed due to water.